The present invention relates to starter-generators. More specifically, the invention relates to a starter-generator circuit that eliminates inadvertent power drainage from a power source.
Starter-generators are used in utility vehicles and equipment having internal combustion engines. Starter-generators are electromagnetic machines that combine the functions of a starter motor and a generator in a single device. A starter-generator is responsible for starting an engine and, once the engine is running, operating as a generator of electrical power. The electrical power is often used to recharge a starting battery and to power devices within or connected to the vehicle or equipment containing the starter-generator. Starter-generators are usually controlled by starter-generator circuits. Often the starter-generator circuit includes a voltage regulator to control the voltage level of generated electrical power.
Starter-generator circuits may also interact with components of the vehicle or device in which they are installed. For example, known utility vehicles are equipped with pedal-actuated-starter-generator circuits, such as the circuit 110 shown in FIG. 1. The circuit 110 includes a ground or ground node 111, a battery 112 with a positive terminal 114, and a two-position key switch 118. The switch 118 includes a ground terminal 120, a magneto terminal 124, a battery terminal 126, and an accessory terminal 128. The switch can be placed in one of two positionsxe2x80x94an off/magneto kill position and a run/accessory power position. When in the off/magneto kill position, the switch 118 couples the magneto terminal 124 to the ground terminal 120. When in the run/accessory power position, the switch 118 couples the battery terminal 126 to the accessory terminal 128. In this position, power from the battery may be supplied to accessories (such as lights, a radio, etc. in the vehicle or device) and to a starter-generator (discussed below).
A pedal activated switch 132 is connected to the accessory terminal 128. When the pedal activated switch 132 is closed (such as when a driver steps on an accelerator pedal of a utility vehicle), a coupling is established between the battery terminal 126 and a first inductor coil terminal 140 of a solenoid 142.
The solenoid 142 has a second inductor coil terminal 144 and an open-in-neutral gearshift switch 152 is coupled to the terminal 144. When the open-in-neutral gearshift switch 152 is closed (such as when a driver places a utility vehicle in gear) a coupling is established between the second inductor coil terminal 144 and ground 111. This energizes the solenoid 142 such that a solenoid switch 148 is closed. When closed, the solenoid switch 148 couples the positive terminal 114 of the battery 112 to a node 155. The node 155 is coupled to an inductor 160. The inductor 160 is coupled to a terminal 161 of a starter-generator 162. The starter-generator 162 is coupled to an engine (not shown). When the engine is off, the starter-generator acts as a starter and uses power supplied from the battery to start the engine. Once the engine starts and the engine speed reaches a certain level, the starter-generator acts as generator and generates current that may be used to recharge the battery 112.
The starter-generator 162 is coupled to a transistor terminal 170 of a voltage regulator 172. The voltage regulator 172 is coupled to the node 155 and regulates the voltage applied to the battery 112 by selectively creating a path between the terminal 161 and the ground.
Another example of a starter-generator circuit is a key actuated starter-generator circuit. Like a pedal-actuated-starter-circuit, a key actuated starter-generator circuit has a multi-position switch coupled to a solenoid relay, a voltage regulator, and a starter-generator. However, a key-actuated starter generator circuit lacks a pedal activated switch and may or may not include a gearshift switch.
The inventors have discovered that a problem with the pedal-actuated-starter-generator circuit 110 and key-actuated starter generator circuits is that so long as the key switch (such as switch 118) remains in the run/accessory power position, accessories can continue to draw power from the battery. In addition, if the engine stalls (in which case the switches 132 and 152 may remain closed in the circuit 110) or operates in such a way that the voltage at the starter-generator is less than the voltage at the positive terminal of the battery, power may be drawn from the battery. In some circumstances it is possible that these demands may deplete the battery. Once depleted, starting the vehicle or device in which the starter-generator is located is impossible until the battery is replaced or recharged with an another mechanism. Accordingly, there is a need for an improved starter-generator circuit such that inadvertent power drainage can be eliminated or reduced.
The invention provides a system for preventing power drain of a battery and utilizes a key actuated starter-generator circuit. The circuit includes a key switch with a plurality of predetermined positions to provide a connection between an electrical power source and a solenoid, and a bypass rectifier to prevent inadvertent drainage of an electrical power source. The solenoid couples the electrical power source to a starter-generator. The circuit also includes a starter-generator to start an engine and to generate power to charge the electrical power source and a voltage regulator to regulate a predetermined voltage applied to the electrical power source. The system may also include a gear-controlled neutrally closed switch to provide a ground for the solenoid.
The inventors also devised a method of starting an engine with a key switch. The method involves turning a key switch to a starting position and energizing a solenoid by an electrical power source. The closing of the solenoid energizes a starter-generator. The method also involves turning the key switch to a running position, and charging the electrical power source by the starter-generator. The method further involves de-energizing the solenoid by moving the key switch to a second predetermined position, or by opening the switched circuit path. The method may further involve keeping a gear in a neutral position. By configuring a rectified circuit path and the solenoid in parallel, and with either the key switched to the second predetermined position or the switched circuit path opened, the electrical power source is recharged by the generator through the rectified circuit path.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.